Chelsea offered 40 million euros for Kalidou Koulibaly

Italian press writes that Chelsea is ready to transfer him Senegalese defender of Naples, Kalidou Koulibaly.
The sum offered by Chelsea is 40 million but Napoli did not want to sell the Senegalese, especially as the president of Napoli as Chelsea threatened to go to court to unofficial attempts to approach the player. Chelsea's Koulibaly I promised a salary of 4 million euros per season, but Napoli's leadership is convinced that the player will extend the agreement with the Italian team.
Koulibaly refused twice before to extend his contract with Napoli, hoping to get more revenue from the Neapolitan with the current or contract. Player's desire to earn a better salary could push him to ask those from Naples to accept the offer proposed by Chelsea.